High voltage measurement means



May9 1939 l E. HUBEL 2,157,823

` HIGH VOLTAGE MEASUREMENT MEANS Filed Feb. 8, 1938 Eugen Hubei,

Patented May 9, 1939 UNITED STAIRS PATENT @FFME Eugen Hubei, Berlin, Germany, assignor to General Electric Company, a corporation of New York Application February 8, 1938, Serial No. 189,428 In Germany February 1'7, 1937 2 Claims.

My invention relates to voltage measuring methods and apparatus and concerns particularly arrangements of the spark gap type.

It is an object of my invention to provide an 5 improved flash-over type voltage measuring 1device in which relatively small electrodes and relatively short spacings may be employed in order to obtain compactness.

Other and further objects and advantages will become apparent as the description proceeds.

In accordance with my invention in its pre ferred form I provide a pair of spherical electrodes between which a voltage Hash-over may take place to indicate the magnitude of the voltage and I enclose the electrodes in an insulating chamber preferably under high pressure. By use of high pressure the spacings between the electrodes for a given voltage and also the diameter of the spheres may be much smaller than in the case of electrodes in the open air. This arrangement results in a considerable saving of space, not alone because the apparatus itself is more compact, but also because the necessary spacing from other apparatus may be reduced.

The invention may be understood more readily from the following detailed description when con- Sider-ed in connection with the accompanying drawing and those features of the invention which are believed to be novel and patentable will be pointed out in the claims appended hereto. The single gure of the drawing is a side elevation with a portion thereof broken away showing one embodiment of my invention.

In the arrangement illustrated, two terminals II and I2 to which the voltage to be measured may be applied are mounted upon a pair of insulators I3 and I4. A pair of electrodes I5 and I6, preferably spherical, are electrically connected to the terminals II and I2 and are enclosed 40 in a pressure chamber formed by a tube I'I of insulating material. Suitable means are provided for maintaining high pressure within the tube I'I for example, a pressure tank I8 communicating with the space within the tubular chamber I1 through tubing I9, preferably insulated, may be provided. The tank I8 may be filled with air or other suitable gas preferably under higher pressure than is needed in the chamber I'I in order that repeated tests under varying pressure may be made or leakage may be compensated for. In order to control the pressure within the chamber I'I a valve 20 at the outlet of the tank I8 may be provided. If desired, the valve 20 may be a three-way valve of a type well-known in the art having a normal position closing the connection between the tank and the communicating tube I9, having a second position for admitting gas und-er pressure to the chamber I'I to increase the pressure therein and a third position for bleeding air or gas from the chamber I'I to reduce 5 the pressure therein. For measuring and controlling the pressure within the chamber I'I a pressure gage 2I may be provided.

I have found Paschs law to be satisfactorily fulfilled by tests made upon my apparatus. That is, 10 for any given break-down or flash-over voltage between the electrodes I5 and I6, the product of the spacing between the electrodes I5 and I and the pressure within the chamber I? is found to be constant. Accordingly7 by maintaining a rela- 15 tively high pressure in chamber I'I, high voltages may be measured by observing the spacing between the electrodes I5 and IE5 at which flash-over results. In order to make measurements in this manner one of the electrodes, for example, elec- 20 trode I6 may be adjustably mounted by securing it to a slidable rod 22 having a set screw 23 for securing it in various positions and a scale 244 may be provided for measuring the displacement of the electrode IB to determine spacing between elec- 25 trodes I5 and I6. It will be understood that a suitable seal between the opening in the terminal I2 through which the rod 22 protrudes is to be provided. For example, an accordion seal 25 may be utilized. It will be understood that the pressure 30 admitting tube I9 is connected to the inside of the terminal I2 in front of the outlet for the rod 22 to avoid interfering with the seal. For facilitating observation of the occurrence of a flashover, the insulating tube I'I may be composed of 35 transparent material, or if desired an instrument for detecting flash-over may be provided. For example, an electric surge indicating instrument 29 mounted upon a bracket 39, carried by the terminal I I, may be inductively couple-d to the 40 circuit of the electrodes I5 and IE by a loop 3I. Upon discharge between the electrodes I5 and I6 the needle 32 will deect momentarily.

Although I have found that satisfactory and convenient measurements may be made by measuring the various displacements of electrodes I5 and I6 it will be understood that my invention is not limited to this arrangement but, if desired, a constant spacing may be maintained and the pressure may be varied. In this case the pressure readings upon the gage 2l at which voltage ash-over takes place will be proportional to the voltage to be measured. If desired, the gage 2l may be calibrated in terms of voltage. Likewise, to extend the range of the apparatus both the spacing of the electrodes and the pressure in chamber I'I may be varied, in which case the voltage is readily determined by applying Paschs law. In order to make up for loss of pressure When making measurements at varying pressures a pump 26 may be provided. The pump 26 may be connected to a suitable portion of the apparatus such as the tube I9 or the pressure tank I8 in any suitable manner as by a tube 21 having a stop cock 2'8 therein.

The voltage between the terminals Il and I2 may be measured by moving the electrodes I5 and I6 together until ash-over takes place or by reducing the pressure in the chamber l1 until flashover takes place. The spacing and pressure at which ash-over takes place may then be measured.

In accordance with the provisions of the patent statutes, I have described the principle of operation of my invention together with the apparatus Which I now consider to represent the best embodiment thereof but I desire to have it understood that the apparatus shown is only illustrative and that the invention may be carried out by other means.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. A voltage measuring apparatus comprising a pressure chamber, a pair of electrodes therein, means for measuring the pressure in the chamber, a surge current indicator and a circuit for inductively coupling the in-dicator to the discharge circuit of the electrodes 2. A voltage measuring apparatus comprising a pressure chamber, a pair of electrodes therein, and indicating means electrically responsive to an electrical discharge between said electrodes for indicating the occurrence of break down between the electrodes.

EUGEN HUBEL, 

